Ceramic additive formulation and method of making

ABSTRACT

A method of making a ceramic glaze formulation having an antimicrobial property for use with a ceramic article. The method comprises fritting an antimicrobial formulation in a flux frit, providing least one unfritted antimicrobial component, providing a silver carrier in a glass matrix, and combining the flux frit, the at least one unfritted component, and the silver carrier in the glass matrix to form the ceramic glaze formulation. The silver carrier is combined at an addition rate based on a dry weight basis of the ceramic glaze formulation. A ceramic glaze additive formulation and ceramic glazed article are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. nonprovisional patent applicationSer. No. 15/064,777, filed on Mar. 9, 2016, in the United States Patentand Trademark Office. The disclosure of which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to ceramic glazes, moreparticularly to a ceramic glaze additive formulation, a method of makingthe ceramic glaze additive formulation, and a ceramic glazed article.

BACKGROUND OF THE INVENTION

There is an increasing desire to have ceramic products haveantimicrobial protection. For example, there is the desire for bothhousehold and commercial purposes for such ceramic products to be freeof germs and bacteria.

Although consumers want such ceramic products to have this functionalfeature, consumers also do not want to sacrifice the appearance of suchceramic products. This includes the appearance of sanitary ware.Sanitary ware typically requires higher firing temperatures and a longertime period.

Sanitary ware requires a significant increase in the amount of zinc togive it the desired aesthetic color and appearance. Bismuth and zinc aretwo of the most difficult antimicrobial components to put into a glaze.Bismuth particles melt at a lower temperature than zinc, and zinc maynot go into solution with the other components of the glaze. At thefiring temperatures (about 2250° F.) and length of firing time (18-24hours) for sanitary ware, both the bismuth and the zinc can causeproblems with increased fluidity and dripping of the glaze. In notblended well, both can cause discolorations. Bismuth produces clearspots in a white glaze, and zinc produces whiter areas. There is alsodimpling. Zinc can also react with chrome and tin to alter the resultingglaze color.

Thus, there is a need for a method and an additive formulation toovercome these problems yet while providing an energy efficientsolution.

SUMMARY OF THE INVENTION

The present invention relates to a ceramic glaze additive formulation, amethod of making the ceramic glaze additive formulation, and a ceramicglazed article.

A method of making a ceramic glaze formulation having an antimicrobialproperty for use with a ceramic article is provided. The methodcomprises fritting an antimicrobial formulation in a flux frit, whereinthe flux frit is present in the ceramic glaze formulation in an amountof 45 weight % to 55 weight %, based on a dry weight basis of theceramic glaze formulation; providing least one unfritted antimicrobialcomponent; providing a silver carrier in a glass matrix; combining theflux frit, the at least one unfritted component, and the silver carrierin the glass matrix to form the ceramic glaze formulation; wherein thesilver carrier is combined at an addition rate of at least 1 weight %based on a dry weight basis of the ceramic glaze formulation.

In another aspect of the invention, the method comprises fritting anantimicrobial formulation in a flux frit, wherein the flux frit ispresent in the ceramic glaze formulation in an amount of 1 weight % to10 weight %, based on a dry weight basis of the ceramic glazeformulation; providing at least one unfritted antimicrobial component;providing a silver carrier in a glass matrix; combining the flux frit,the at least one unfritted antimicrobial component, and the silvercarrier in the glass matrix to form the ceramic glaze formulation;wherein the silver carrier is added to the ceramic glaze formulation atan addition rate of at least 10 weight % based on a dry weight basis ofthe ceramic glaze formulation.

A ceramic glaze additive formulation is provided comprising: 0.1% to 1%by weight of silver carrier; 12% to 21% by weight of Bi₂O₃; 29% to 37%by weight of ZnO; and 45% to 55% by weight of flux fit, wherein a weightpercentage is based upon the weight of the ceramic glaze additiveformulation.

Another ceramic glaze additive formulation is provided comprising: 5% to15% by weight of silver carrier; 80% to 90% by weight of ZnO; and 1% to10% by weight of flux frit, wherein a weight percentage is based uponthe weight of the ceramic glaze additive formulation.

A ceramic glazed article is provided comprising a ceramic glaze additiveformulation applied on a surface of the ceramic article, the ceramicglaze additive formulation comprising: 0.1% to 1% by weight of silvercarrier; 12% to 21% by weight of Bi₂O₃; 29% to 37% by weight of ZnO; and45% to 55% by weight of flux fit, wherein a weight percentage is basedupon the weight of the ceramic glaze additive formulation.

In still yet another aspect of the invention, another ceramic glazedarticle is provided comprising a ceramic glaze additive formulationcomprising: 5% to 15% by weight of silver carrier; 80% to 90% by weightof ZnO; and 1% to 10% by weight of flux frit, wherein a weightpercentage is based upon the weight of the ceramic glaze additiveformulation.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiments of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the embodiments of the present invention ismerely exemplary in nature and is in no way intended to limit theinvention, its application, or uses. The present invention has broadpotential application and utility, which is contemplated to be adaptableacross a wide range of industries. The following description is providedherein solely by way of example for purposes of providing an enablingdisclosure of the invention, but does not limit the scope or substanceof the invention.

As used herein, the terms “microbe” or “microbial” should be interpretedto refer to any of the microscopic organisms studied by microbiologistsor found in the use environment of a ceramic article or ceramic-glazedarticle. Such organisms include, but are not limited to, bacteria andfungi as well as other single-celled organisms such as mold, mildew andalgae. Viral particles and other infectious agents are also included inthe term microbe.

The term “antimicrobial” includes biostatic activity, i.e., where theproliferation of microbiological species is reduced or eliminated, andtrue biocidal activity where microbiological species are killed. Forease of discussion, this detailed description may make reference tobacteria and antibacterial agents. This method of presentation shouldnot be interpreted as limiting the scope of the invention in any way. Aswell, “antimicrobial” and like terms should be interpreted asencompassing both microbe-killing as well as microbiostatic activities.That is, it herein is considered efficacious if an antimicrobialcomposition reduces the number of microbes on a substrate or it thecomposition retards the normal rate of microbial growth.

For ease of discussion, this description uses the terms microbes andantimicrobial to denote a broad spectrum activity (e.g. against bacteriaand fungi). When speaking of efficacy against a particular microorganismor taxonomic rank, the more focused term will be used (e.g. antifungalto denote efficacy against fungal growth in particular). For ease ofdiscussion, this description uses the terms microbes and antimicrobialto denote a broad spectrum activity (e.g. against bacteria and fungi).When speaking of efficacy against a particular microorganism ortaxonomic rank, the more focused term will be used (e.g. antifungal todenote efficacy against fungal growth in particular).

Using the above example, it should be understood that efficacy againstfungi does not in any way preclude the possibility that the sameantimicrobial composition demonstrates efficacy against another class.

For example, discussion of the strong bacterial efficacy demonstrated bya disclosed embodiment should not be read to exclude the embodiment fromalso demonstrating antifungal activity. This method of presentationshould not be interpreted as limiting the scope of the invention in anyway.

Glazes are generally made from powdered glass combined with coloredoxides of such elements as cobalt, chrome, manganese, or nickel. Thepowder mixture is suspended in water and applied to the ceramic surfaceby spraying, brushing, dipping, or other known application methods.

The suspension, or slip, in which the glaze is applied to the ceramicsurface must have particular properties to ensure that the glaze is easyto apply, does not run during glaze application, and adheres well bothwhen wet and after firing. These slip properties are often obtained byadding a small amount of clay to the suspension and by controlling boththe amount of water in the slip as well as the size of the powderparticles. Organic surface-active agents (e.g. surfactants, detergents)also can be added to the slip to improve its properties. Colors inglazes are controlled by adding coloring agents to the glassy componentsof the glaze.

A ceramic production glaze formulation is a combination of ceramicmaterials that have been developed for production application tospecific ceramic articles. A ceramic glaze additive formulation is acombination of antimicrobial components that are combined in a ceramicproduction glaze formulation to result in an antimicrobial ceramicproduction glaze formulation.

The ceramic glaze additive formulation of the present inventioncomprises a fritted antimicrobial composition, an unfrittedantimicrobial component(s), and a silver carrier in a glass matrix.

As used herein, “fritting” means melting an antimicrobial agent(s) orconstituent(s) into a glass, quenching the glass to freeze the amorphouscondition, and then grinding to a desired particle size. The frittedantimicrobial composition is a more homogeneous composition and allowshigher amounts of the components than is acceptable in the oxide form.Using a flux frit as the entire source or the partial source of theantimicrobial components permits a much wider range of compositions.Fritting the composition creates an antimicrobial additive that is moreeasily combined with a base (untreated) glaze. The fritted material isalso better tolerated in faster firing cycles with a reduction insurface defects due to varying firing cycles with a reduction in surfacedefects due to varying melting points and viscosities. The frittedmaterial has fewer firing limitations because the dissociation of itscomponents has already occurred during fritting.

The fritted antimicrobial composition comprises an antimicrobialselected from the group consisting of bismuth oxide (Bi₂O₃), zinc oxide(ZnO), and a combination thereof.

The unfritted components are selected from the group consisting ofbismuth oxide (Bi₂O₃), zinc oxide (ZnO), and a combination thereof.

In an embodiment of the present invention, a first ceramic glazeformulation is provided. The first ceramic glaze formulation comprises0.1% to 1% by weight of silver carrier; 12% to 21% by weight of Bi₂O₃;29% to 37% by weight of ZnO; and 45% to 55% by weight of flux frit,based upon the weight of the ceramic glaze formulation.

In an embodiment of the present invention, a second ceramic glazeformulation is provided. The second ceramic glaze formulation comprises5% to 15% by weight of silver carrier; 80% to 90% by weight of ZnO; and1% to 10% by weight of flux fit, based upon the weight of the ceramicglaze formulation.

In accordance with the present invention, a method of making a ceramicglaze having an antimicrobial property for use with a ceramic article isprovided.

Those skilled in the art recognize that the production process ofceramic products may vary from that which is presented below, and thatthe ceramic glazing process disclosed herein is adaptable to othersubstrates.

In a first embodiment of the method, the method generally comprisesfritting an antimicrobial formulation in a flux frit, wherein the fluxfrit is present in the ceramic glaze formulation in an amount of 45weight % to 55 weight %, based on a dry weight basis of the ceramicglaze formulation; providing at least one unfritted antimicrobialcomponent; providing a silver carrier in a glass matrix; combining theflux frit, the at least one unfritted antimicrobial component, and thesilver carrier in the glass matrix to form the ceramic glazeformulation. The silver carrier is combined at an addition rate of atleast 1 weight % based on a dry weight basis of the glaze formulation.

In a second embodiment of the method, the method generally comprisesfritting an antimicrobial formulation in a flux frit, wherein the fluxfrit is present in the ceramic glaze additive formulation in an amountof 1 weight % to 10 weight %, based on a dry weight basis of the ceramicglaze formulation; providing at least one unfritted antimicrobialcomponent; providing a silver carrier in a glass matrix; combining theflux frit, the at least one unfritted antimicrobial component, and thesilver carrier in the glass matrix to form the ceramic glazeformulation. The silver carrier is combined at an addition rate of atleast 10 weight % based on a dry weight basis of the ceramic glazeformulation.

There are numerous methods by which the silver carrier can be combinedwith the flux frit. The silver carrier can be mixed into the frit. Itmay require a larger amount of silver ions on the surface of thecarrier. Another method by which the silver carrier can be combined withthe flux frit is by a treatment material such as a chemical bath. It ispossible to preferentially put silver into a glass matrix such that itis on the surface of the carrier.

In an aspect of the method, the antimicrobial formulation comprises anantimicrobial selected from the group consisting of zinc oxide, bismuthoxide, titanium oxide, tin oxide, silver compound, and a combinationthereof. In a preferred aspect of the invention, the antimicrobialformulation comprises an antimicrobial selected from the groupconsisting of bismuth oxide, zinc oxide, and a combination thereof. Itwas surprisingly found that there is a synergistic effect with zincoxide and bismuth oxide in certain combinations when used in the methodof this invention.

In another aspect of the method, the flux frit further comprises a glassformer. The glass formers are typically glass constituents having noefficacious history.

In an aspect of the method, Bi₂O₃ is present in the flux frit in a rangeof 50% to 56% by weight, preferably in a range of 52% to 54% by weight,of the flux fit.

In an aspect of the invention, ZnO is present in the flux fit in a rangeof 1% to 5% by weight, of the flux frit.

In an aspect of the first embodiment of the method, unfritted Bi₂O₃ ispresent in the ceramic glaze formulation in a range of 12% to 20% byweight, preferably in a range of 14% to 18% by weight, of the ceramicglaze formulation.

In an aspect of the first embodiment of the method, unfitted ZnO ispresent in the ceramic glaze formulation in a range of 29% to 37% byweight, preferably in a range of 31% to 35% by weight, of the ceramicglaze formulation.

In an aspect of the second embodiment of the method, unfritted Bi₂O₃ ispresent in the ceramic glaze formulation in a range of 0% to 5% byweight, preferably 0% by weight, of the ceramic glaze formulation.

In an aspect of the second embodiment of the method, unfritted ZnO ispresent in the ceramic glaze formulation in a range of 80% to 90% byweight, preferably in a range of 83% to 87% by weight, of the ceramicglaze formulation.

In another embodiment of the present invention, a ceramic article isprovided. The ceramic glazed article comprises a fritted antimicrobialcomposition comprising an antimicrobial selected from the groupconsisting of bismuth oxide, zinc oxide, and a combination thereof; anda silver carrier in a glass matrix.

In an aspect of a first embodiment of the invention, the bismuth oxideis present in a range of 59% to 68% by weight of the ceramic glazeformulation, zinc oxide is present in an amount of 30% to 40% by weightof the ceramic glaze formulation, and the silver carrier is present in arange of 0.1% to 1% by weight of the ceramic glaze formulation.

In an aspect of a second embodiment of the invention, the bismuth oxideis present in a range of 0% to 10% by weight of the ceramic glazeformulation, zinc oxide is present in an amount of 80% to 90% by weightof the ceramic glaze formulation, and the silver carrier is present in arange of 5% to 15% by weight of the ceramic glaze formulation.

The ceramic article of the present invention is any article having aceramic glaze including, but not limited to, toilets, bidets,washbasins, towel rails, soap holders, toilet roll holders, watercontrol fixtures (e.g., hot and cold water handles), and tiles.

These ceramic glaze additive formulations were surprisingly found toachieve the appearance and color that is needed of the finished ceramicarticle yet overcome energy and cost inefficiencies associated with onlyhaving a fritted antimicrobial composition. Fritting is energy intensivedue to the energy required with melting, cooling, grinding and any sizeseparation.

The present invention surprisingly solves the need of making fasterfired ceramic articles. The term “faster fired” refers to a shorter timerequired for the ceramic article to cycle through the kiln whilemaintaining the required properties and quality produced using thelonger firing time. For example, the method reduces the firing time forvarious components of the glaze formulation. When subjected to heat, aceramic formulation goes through various combinations of time andtemperature (heat treatment) in a kiln to develop a vitreous orcrystalline bond necessary to provide the properties associate with aceramic material. This heat treatment (combination of time andtemperature) is necessary to remove those materials which are given offat various points within the kiln. Examples of these are water offormation, chemical water, carbonates, phosphates, and all includedorganic materials. These are also known as “products of combustion” or“loss on ignition”. Sufficient time must be provided for these materialsto be expelled before the next time/temperature combination is reached.When the components of a glaze formulation are added as frit(s), all orpart of the materials that would give off water, carbonates, etc., havebeen pre-fired to a glassy state, quenched, and ground to the propersize (frit), there is no reason to slow down the heat treatment. All ofthe reactions for the “products of combustion” have taken place duringthe fitting operation. Additionally, the method eliminates surfacetexture problems such as the hammered look that is seen on glossy glazeswhen an antimicrobial is added as a mixture of components.

In still yet another aspect of the method, it was surprisingly foundthat when a ceramic production glaze formulation, that is to be appliedto a ceramic production substrate or article, comprises about 2 weight %to about 12 weight % on a dry weight basis of zinc oxide that it ispossible to reduce the amount of zinc oxide in the antimicrobialaddition. Thus, as a feature of the present invention, the amount ofzinc oxide can range from 0 weight % to 10 weight % in the antimicrobialformulation depending upon the amount of zinc oxide already present inthe ceramic production glaze formulation. This is as a component of theantimicrobial formulation that is then added to the ceramic productionglaze formulation at 4 weight % to 10 weight % on a dry weight basis.

The fritting method of the present invention can be used to implementthe different antimicrobial combinations into an untreated glaze or asan application of these materials in an aqueous solution or organiccarrier onto the top surface of an unfired glaze.

It will therefore be readily understood by those persons skilled in theart that the present invention is susceptible of broad utility andapplication. Many embodiments and adaptations of the present inventionother than those herein described, as well as many variations,modifications and equivalent arrangements, will be apparent from orreasonably suggested by the present invention and the foregoingdescription thereof, without departing from the substance or scope ofthe present invention. Accordingly, while the present invention has beendescribed herein in detail in relation to its preferred embodiment, itis to be understood that this disclosure is only illustrative andexemplary of the present invention and is made merely for purposes ofproviding a full and enabling disclosure of the invention. The foregoingdisclosure is not intended or to be construed to limit the presentinvention or otherwise to exclude any such other embodiments,adaptations, variations, modifications and equivalent arrangements.

What is claimed is:
 1. A ceramic glaze additive formulation comprising:0.1% to 1% by weight of silver carrier; 12% to 21% by weight of Bi₂O₃;29% to 37% by weight of ZnO; and 45% to 55% by weight of flux frit;wherein a weight percentage is based upon the weight of the ceramicglaze additive formulation.
 2. A ceramic glazed article comprising theceramic glaze additive formulation of claim 1 applied on a surface ofthe ceramic article.
 3. A ceramic glaze additive formulation comprising:5% to 15% by weight of silver carrier; 80% to 90% by weight of ZnO; and1% to 10% by weight of flux frit; wherein a weight percentage is basedupon the weight of the ceramic glaze additive formulation.
 4. A ceramicglazed article comprising the ceramic glaze additive formulation ofclaim 3 applied on a surface of the ceramic article.